CircuitBreaker
| Project CircuitBreaker | |
|---|---|
| A small configurable electronic circuit breaker that can be placed between your laptop or USB power supply and anything you happen to be working on. | |
| Status | In progress |
| Contact | thomas |
| Last Update | 2016-12-24 |
The idea is to use an ACS712 allegra current sensing module to keep an eye on the current drawn by anything connected to a USB port or USB power supply, and to break the circuit when whatever you're working on draws a little more juice than you expected it to. This is mostly meant for working with an Arduino, ESP8266 or other micro, with or without additional (breadboarded) circuitry attached. You could just use a current limited power supply, but they tend to be rather cumbersome, and this design includes the whiz-bang option of feeding data through it. This means that you can upload your program to the micro, monitor current draw and presumably protect both your USB port and target circuit from emitting unwanted smoke, all with just one device.
Features
This project will include a micro USB input, a relay or MOSFET for switching VDD, an ACS712 current sensor and a normal USB female connector for plugging in your target circuit. The display consists of 12 LEDs, 6 of which displaying actual current consumption, and the remaining 6 displaying current trip point of the breaker. Due to the relative inaccuracy of the ACS712 module, the trip point can only be selected from 6 preprogrammed values. These will range between 100mA and 1A or 1.5A.
The unit will include a pot for selecting current trip point, as well as a reset button and a trip button. I may add a 3.3v regulator and output both 3.3v and 5v banana connectors, also feeding from the current sensed supply.
Materials
I haven't decided on the details of the circuit. Depending on the stability of the ACS712, I may change the filter capacitor on the module as per the datasheet. This will give you reduced noise and hence accuracy, but it will reduce the speed of the breaker. The output of the ACS712 will feed into the A/D of an arduino. For switching, I will use either a relay or a mosfet.
The case is a small ancient aluminium project box rescued from the recycling bin. I just need to find some screws to put it together, but the holes for the connectors, buttons and leds are drilled, and the proto-pcb is mounted.